Several mail servers are available on the market today. Some are rather confounding to configure but are super-reliable. Others are a little old school and rely on no small degree of background knowledge to get them up and running.
According to the website Mail Radar, in a randomized survey of 59,...

In the previous article, I looked at some pre-greeting tests that Postfix performs to help identify spam; now I’ll move on through the chain and explore the available post-salutation tests. Remember that limiting how many machines make it to this stage is of significant value to a mail server’s...